A videotape recorder (hereinafter referred to as VTR) which has heretofore been used in homes as a magnetic recording and reproducing device for recording and reproducing images is, in use, loaded with a videotape cassette (hereinafter referred to simply as cassette) to record or reproduce images such as television programs. As for cassette loading systems, almost all VTR's have recently employed the front loading system.
In such conventional VTR, an outline will now be given of the cassette loader for loading a cassette in the recording and reproducing position so as to record or reproduce information or images such as television programs.
FIG. 3 is a schematic structural view showing the vicinity of the cassette loader of a VTR which is a conventional magnetic recording and reproducing device. As shown in FIG. 3, the cassette loader 1 comprises a cassette holder 6 which is disposed inwardly of a cassette insertion port 3 formed in a front panel 2 and which, while holding on a mechanism base of metal 4 a cassette 5 containing a recording medium for recording visual information and acoustic information thereon, moves the cassette to a recording and reproducing position where recording and reproducing is allowed, and a holding, moving and driving unit 9 adapted to be pivoted around the axis J1 of a pivot shaft 7 to thereby drive the cassette holder 6 such that the cassette holder 6 moves in the direction of arrow Y1 through engaging portion 8 which engages a projection 6a formed on the cassette holder 6, the arrangement being such that the movement of the cassette holder 6 in the direction of arrow Y1 results in loading the cassette 5 in the recording and reproducing position.
In the above arrangement, the holding, moving and driving unit 9 is engaged with a drive transmission bar 12 through a gear 10 formed on the axis j1, said drive transmission bar 12 being formed with an arcuate rack 11 which meshes with said gear 10, said drive transmission bar 12 being driven by a motor in the direction of arrow y2 to drive the gear 10 for rotation, thereby pivoting the holding, moving and driving unit 9 around the axis J1 of the pivot shaft 7.
In this case, the pivot shaft 7 around whose axis j1 the holding, moving and driving unit 9 is pivoted is directly supported by bearings 15 and 16 formed as holes in lateral plates 13 and 14 attached to the opposite sides of the mechanism base 4, said lateral plates 13 and 14 being provided in recent years in the form of resin moldings for the sake of reducing the weight and cost of the device.
Referring to the cassette loader 6 constructed in the manner described above, its operation will now be described. The outline of the operation of the cassette loader 1 to be given herein extends from the initial state prior to cassette loading to the cassette loading completion state, i.e., the final phase in which a cassette 5 has been loaded in the recording and reproducing position.
FIG. 4 shows a state prior to the loading of a cassette by the cassette loader 1 and FIG. 5 shows a cassette loading completion state.
As shown in FIG. 4, when the cassette 5 is loaded in the cassette holder 6 as shown by an arrow Y3, this loaded state is detected to rotate a motor (not shown), whereby the drive transmission bar 12 is slid in the direction of arrow Y4. This slide movement of the drive transmission bar 12 effects the rotation of the gear 10 of the holding, moving and driving unit 9 meshing with the arcuate rack 11 of the drive transmission bar 12 and concurrently therewith the holding, moving and driving unit 9 is pivoted around the axis j1 of the pivot shaft 7 in the direction of arrow Y5.
As a result of this pivotal movement of the holding, moving and driving unit 9, the cassette holder 6, with the cassette 5 held therein, is moved in the direction of arrow Y6 while sliding the projections 6a and 6b along guide grooves 13a and 13b formed in the lateral plate 13, because the projection 6a is engaged with the engaging portion 8 of the holding, moving and driving unit 9.
Further, as shown in FIG. 5, when the drive transmission bar 12 is slid in the direction of arrow Y7, the holding, moving and driving unit 9 is further pivoted in the direction of the direction of arrow Y8, and the cassette holder 6 is moved in the direction of arrow Y9 while further sliding the projections 6a and 6b engaging the engaging portion 8 of the holding, moving and driving unit 9 along the guide grooves 13a and 13b.
In this manner, the cassette holder 6 comes to be disposed in the recording and reproducing position, and hence the cassette held in this cassette holder 6 is loaded in the recording and reproducing position, so that the magnetic tape which is a recording medium held in the cassette is ready to record or reproduce visual and acoustic information contained in television programs.
In addition, as shown in FIG. 5, cassette pressers 20 are installed on both sides of the cassette holder 6 to press the upper surface of the cassette 5 held therein so as to prevent the cassette 5 from slipping off, and a spring member 20a having an elastic force is attached to the region of each cassette presser 20 which abuts against the cassette.
Further, as shown in FIG. 5, the holding, moving and driving unit 9 has projection pressing springs 21 attached thereto 21 for pressing the projections 6a to prevent the latter from rattling.
This known type of magnetic recording and reproducing device has the following drawback.
In the conventional examples shown in FIGS. 3 through 5, when the cassette holder with a cassette 5 held therein is moved to the recording and reproducing position where the cassette 5 is loaded for recording or reproducing purposes, pressing forces exerted by the cassette pressers 20 act on the cassette 5 through the spring members 20a in the direction of arrow Y9.
Owing to these pressing forces, reversely, reaction forces exerted by the cassette 5 act on the cassette pressers 20 through the spring members 20a in the direction of arrow Y10, and concurrently with these reaction forces there occur reaction forces exerted by the projections 6a of the cassette holder 6 to which the cassette pressers 20 is attached which reaction forces act on the projection pressing springs 21 in the direction of arrow Y11, these reaction forces being followed by forces exerted by the pivot shaft 7 which act on the bearing portions 15 and 16 of the lateral plates 13 and 14 in the direction of arrow Y12.
If, therefore, the situation in which the cassette 5 is held in its loaded state in the recording and reproducing position for a long time occurs frequently, this leads to the result that the portions of the inner surfaces of the bearing portions 15 and 16 of the lateral plates 13 and 14 of resin which are acted on by the forces in the direction of arrow Y12 are deformed in the direction of arrow Y12. That is, the lateral plates 13 and 14 including the bearing portions 15 and 16 are deformed in the direction of arrow Y12 and the engaging portion 8 of the holding, moving and driving unit 9 is moved in the direction of arrow Y11 and so the cassette holder 6 is moved also in the direction of arrow Y11. Therefore, the reel (not shown) of the cassette 5 placed in the cassette holder 6 is disengaged from reel blocks R1, so that the driving forces exerted by the reel blocks R1 are not fully transmitted to the reel of the cassette 5, thus detracting from the reliability of the device itself.